Alkaline electrochemical cells are commercially available in cell sizes commonly known as LR6 (AA), LR03 (AAA), LR14 (C) and LR20 (D). The cells have a cylindrical shape that must comply with the dimensional standards that are set by organizations such as the International Electrotechnical Commission. The electrochemical cells are utilized by consumers to power a wide range of electrical devices, for example, clocks, radios, toys, electronic games, film cameras generally including a flashbulb unit, as well as digital cameras. Such electrical devices possess a wide range of electrical discharge conditions, such as from low drain to relatively high drain. Due to the increased use of high drain devices, such as digital cameras, it is desirable for a manufacturer to produce a battery that possesses desirable high drain discharge properties.
As the shape and size of the batteries are often fixed, battery manufacturers must modify cell characteristics to provide increased performance. Attempts to address the problem of how to improve a battery's performance in a particular device, such as a digital camera, have usually involved changes to the cell's internal construction. For example, cell construction has been modified by increasing the quantity of active materials utilized within the cell.
U.S. Pat. No. 4,777,100 relates to reportedly reducing corrosion in aqueous electrochemical cells having zinc anodes comprised of single crystal zinc particles by the addition of small amounts of a gas inhibiting surfactant, for example, an organic phosphate inhibitor such as RA600 from GAF Corp. to the cell. A synergistically lowered rate of corrosion and cell gassing is reportedly obtained even with reduction of mercury content.
U.S. Pat. No. 5,401,590 relates to a method for inhibiting the occurrence of load voltage instability in zinc anodic alkaline cells. The anode active material contains a gelled slurry of zinc alloy particles, a gelling agent, an aqueous alkaline solution and a mixed surfactant containing an anionic surfactant and a nonionic surfactant. The gelled anode active material reportedly inhibits the occurrence of load voltage instability and reportedly simultaneously reduces hydrogen evolution even though the cell contains no added amounts of mercury.
U.S. Pat. No. 6,872,489 discloses a sulfonic acid type organic surfactant which is incorporated into the gelled anode of an alkaline electrochemical cell, optionally with an organic phosphate ester surfactant. When the two surfactants are provided in a gelled anode in combination, discharge leakage is reportedly reduced and gel gassing is reportedly suppressed relative to that of gels lacking both surfactants. Additionally, cell discharge performance is reportedly improved relative to that of cells lacking both surfactant additives.
U.S. Pat. No. 7,008,723 relates to a method of manufacturing an anode composition for use in an electrochemical cell, in which the anode comprises an electrochemically active material, the method comprising the steps of mixing the electrochemically active material with an alkaline electrolyte solution, an organic surfactant, an indium compound, and a gelling agent, such that the indium compound or a portion thereof is added in an alkaline environment.
U.S. Pat. No. 7,045,252 relates to an alkaline battery which includes a cathode including lambda-manganese dioxide and gamma-manganese dioxide, an anode including zinc, a separator between the cathode and the anode, and an alkaline electrolyte contacting the anode and the cathode.
U.S. Pat. No. 7,056,617 relates to a non-hermetically sealed, electrochemical power source, including a first electrode, a second electrode, a separator between the first electrode and the second electrode, and a membrane in fluid communication with an environment external to the battery. The second electrode is between the separator and the membrane. The membrane includes a first portion having a different property, e.g., density, porosity, mass transport resistance, thickness, or gas permeability, than a second portion of the membrane. Methods of designing an electrochemical cell cartridge are also disclosed.
U.S. Pat. No. 7,066,970 relates to electrochemical cells and methods of making cells. In some embodiments, an electrochemical cell includes a housing, a negative electrode in the housing, a positive electrode in the hosing, the positive electrode including a wax, and a separator between the negative and positive electrodes.
U.S. Publication No. 2005/0123833 relates to a copolymer of an ethylenically unsaturated carboxylic acid, e.g., acrylic or methacrylic acid, and an aromatic sulphonate or carboxylate, e.g., sodium styrene sulphonate, either alone or supported on a substrate, that may be used as a separator for an electrochemical cell such as a silver-zinc cell or a zinc-air cell.
U.S. Publication No. 2006/0068288 relates to an alkaline electrochemical cell capable of providing optimum discharge efficiencies at both a high tech drain rate and a low drain rate. In one embodiment, the ratio of the anode's electrochemical capacity to the cathode's electrochemical capacity is between 1.33:1 and 1.40:1 and the surface area of the anode to cathode interface is maximized.
Japanese Publication No. 59-035360 relates to reportedly increasing cycle life by forming a zinc electrode of an alkaline electrode with an active material prepared by adding hydrophilic short fiber, an additive, and a binder to zinc oxide powder and metal zinc powder both having a specified particle size.